Esophageal cancer (ECa) has become the 6th leading cause of cancer death in the world, and its incidence rate continues to increase worldwide. Unfortunately, most patients with esophageal cancer have advanced disease at the time of initial diagnosis and ineligible for curative surgical resection. Recently, multimodality therapies have been attempted to improve the resectability of tumors and the long-term survival of patients. Among them, concurrent chemoradiation therapy (CCRT) in a neoadjuvant setting followed by esophagogastrectomy has been widely applied in current clinical practice. However, it is found that individual variation in response to CCRT exists and is associated with different treatment outcomes. Patients with a complete response to CCRT tends to have an increased survival rate, but survival of patients without an evident response to CCRT may be compromised due to treatment-related toxicity and delays in surgical resection. Although studies have focused for biomarkers associated with the patients' response to chemoradiotherapy (The pharmacogenomics journal 2009; 9:202-7; Cancer Lett 2008; 260:109-17; and Int J Cancer 2008; 123:826-30), no reliable genetic markers are currently available.
There is still a need for a genetic marker that is predictive of an ECa patient's response to chemoradiotherapy, and thus helpful in preventing unnecessary treatments and determining the most appropriate treatment for patients.